Can events that occurred during pregnancy have caused my child’s autism?

“Got Questions?” is a new weekly feature on our blog to address the desire for scientific understanding in our community. We received over 3000 responses when we asked what science questions were on your mind. We answered a few here and the Autism Speaks Science staff will address the other themes we received in this weekly post.

Many families have emailed us and asked what exposures in pregnancy result in an increased risk for an Autism Spectrum Disorder diagnosis. The answer is not simple. No single environmental factor or single gene is responsible for causing ASD. Instead research suggests that a combination of multiple genetic and environmental factors lead to the multiple symptoms of autism.

By studying large populations, research on environmental exposures in autism has identified some exposures that increase the risk of autism in specific populations. Interestingly, these exposures have been linked to poor neurological outcome in general, and may lead to a wider range of neurodevelopmental conditions that includes autism. Three exposures have been shown to increase the risk for ASD in at least two published studies:

Pesticides: Two separate studies examining families living in California reported an increased risk of autism spectrum disorders following prenatal pesticide exposure. In the first study, Dr. Brenda Eskinazi at the University of California Berkley studied a group of Mexican-American children with known organophosphate exposures. She found that children who had increased levels of the break-down products of these pesticides were more likely to have impaired cognitive development at young ages as well an increased risk for pervasive developmental disorder (as reported by parents). In another study, Dr. Eric Roberts and his colleagues at the California Department of Public Health used informational databases to study possible connections between an ASD diagnosis and organochlorine pesticide exposure during different points of gestation. They found that those living closest to the area of pesticide application early in the 2nd trimester of pregnancy were at the highest risk for developing ASD.

Following up on these epidemiological studies, Autism Speaks is funding researchers who are utilizing animal models to determine possible genetic susceptibilities and neurobiological mechanisms. For example, animals that have been bred to display an altered expression of the REELIN protein show particular sensitivity to organophosphate pesticides. Prenatal exposure to organophosphates disturbs the migration of developing neurons especially in animals that have lower levels of REELIN. Altered effects on the developing neurons can lead to atypically-connected adult brain circuits—a finding commonly observed in ASD.

Valproic Acid: Valproic Acid, or Valproate, is an anti-epileptic drug which targets the GABA receptor in the brain and has been effectively used to treat seizures. When taken by the mother during the first few weeks of pregnancy, it can cause limb malformations, developmental delays, and musculoskeletal abnormalities, called “fetal valproate syndrome”. The first report of autism in an individual with fetal valproate syndrome was published in 1994, with follow up in an animal model soon after. Since then, four epidemiological studies have been published which show an increased rate of autism compared to the general population in individuals exposed prenatally with valproic acid. In an animal model, valproic acid results in some of the same neuropathological and behavioral abnormalities seen in autism: reduction in cerebellar Purkinje cells and an increase in social impairment.

Because this is a drug used to treat a life-threatening illness, women with epilepsy should consult their obstetrician before stopping this or any prescribed medication. Interestingly, the use of other anti-epileptic drugs during pregnancy has not revealed any elevated risk for ASD. The differences in the detailed mechanism of action between valproate and other anti-epileptic drugs may inform our understanding of the causes of autism. Autism Speaks is supporting two investigations into the biological mechanisms that lead to brain and behavioral changes after prenatal exposure to valproate

Challenges to the immune system: Multiple lines of converging evidence suggest that the immune system plays a significant role in ASD. This evidence includes studies that analyze the immune system profiles of mothers of children with autism, as well as the immune system of individuals with autism themselves. Family history of autoimmunity or immune dysfunction and a history of bacterial infection in mothers have been associated with an increased risk of ASD. More targeted studies on how immune system activation during pregnancy affects outcome in animal models are being funded by Autism Speaks to determine how the nature, origin, and timing of immune system activation can influence the developing brain.

Numerous other exposures have been studied and have shown an elevated risk but are still in the early stages of analysis. These include, but are not limited to: phthalates (substances added to plastics), in-vitro fertilization technologies, terbutaline (a treatment used to delay premature labor), and extreme maternal stress.

In addition to environmental exposures, factors such as parental age and season of birth are likely to play a role in how the body handles exposure during the reproductive years. For more information on what studies Autism Speaks is funding on environmental risk factors for autism, please click here.

While individual studies are needed to identify potential exposures of interest, participation and support in these studies is essential to allow researchers to study these questions. Three major Autism Speaks-supported studies currently addressing these questions are the CHARGE study, the EARLI study, and the Infant Brain Imaging Study. Another important study examining environmental risk factors related to health, including autism is the National Children’s Study. Each study employs a unique design to recruit families and identify individuals with ASD for better identification and evaluation of exposures of interest, and all of them have great potential to shed light on prenatal risk factors for ASD.

I was on terbutaline PO for one week, then magnesium sulfate for 24 hours after being admitted for pre-term labor and was sent home on a terbutaline pump for 4 weeks. My daughter who just turned 12 was recently diagnosed with an autism spectrum disorder; we have been trying to get help for her since she could walk (at 13 months old).

I think it has to do with a combination of above theories and all the chemicals we are exposed to in our daily lives. I was working full time on my feet and very stressed from work and in my late second trimester developed hypertenion and preeclampsia. Maybe thats why my child was diagnosed with ASD. We need to find out whats going on.

I have 3 son’s all very close in age, my middle son Adam 21 is Autistic and i think it was because i had my appendix removed well 4 months pregnant i did have many pain killers in hospital doc/nurses saying it would be ok to take them,i was really ill afterwards to .my two other son’s have no problems at all Matt is 22 and Tom is 18,no known Autism in either side of families.I would love to know what causes it and a cure because it breaks my heart to see my Adam suffer so bad some days he’s very complex and i still feel awful and quilty and wonder why he’s Autistic.I think it’s on the increase to from when my son’s were small.

Not that my experience is a scientific fact or anything but…when I had my 1st child, whos is not autistic, I was only 21 and working as a waitress. When I had my second child, who is autistic, I was 27 and worked for a pest control company. I never went into the storage shed but the technicians were in and out of the office all day and I was in contact with them. The company that I worked for did not use any organophosphates or cabamates but there were all manner of pyrethrins and other pesticides. It may just be a horrible coincidence.

I was in the Persian Gulf before I got pregnant and took the mysterious white pills and the shots. Also, I had complications during my pregnancy to include preeclampsia. My son had meningitis at 3 weeks old. Did any and / or all of this contribute to his Autism.

We all suspect Vaccines and Pesticides…we just need someone out there to Prove it in a GOOD/Well put together study. Bacterias & viruses have gotten into vaccines and there have been recalls. We called in a vaccine reaction at 10 months due to inflammation from the FLU shot. Not many studies out there for the FLU shots. Don’t you think there should be???? When I went for my first colonoscopy this year, I found it very interesting that they asked me if I got Last Years Flu shot. Things should be “out in the Open” / when you hide things or don’t even put money into something that hundreds of thousands of people “suspect”, something is wrong. WHAT HAS BEEN DONE ABOUT PESTICIDES? I also read that this years FLU vaccine (imported) had a high incidence of causing SEIZURES in children under 5!!!! WHAT WAS DONE, they changed the label?? that they never give the parents! DISGUSTING! Wake up America and Protect your kids from Greed!!! SEIZURES OR FLU? You make the call!

I have wondered about this for the last 25 years. My husband is a farmer and I always handled his clothing that may have had herbicide/pesticide on it, plus I had a mouth full of mercury amalgam fillings.

I have a friend who has an 8 year old son who has autism. He is becoming violent towards his teachers at school. Mainly this is caused by him losing a game weather its with other kids or even by himself. Do you have any ideas what she or his teachers can do so that he does not hit them or become violent towards them when he does not win>

If you are pregnant stay away from pesticides! Weeds are a small price to pay. I would not even garden.

As for this emphasis on Valporic Acid- how many Moms really took that while pregnant? I get so tired of that one. 99% of ASD Moms engaged in no obvious risky behavior. Let’s deal in reality. We know any prescribed drug is risky- so stay away from it if you can. I would not take Pitocin if I could avoid it. It is so hard to trust any drug is safe to take while pregnant.

For pete’s sake we need to study vaccinating pregnant women! The flu shot still has mercury in it- that is insane for pregnant women to have. We need SHORT TERM studies now.

I have twin daughters (fraternal). They were 4 weeks premature and I had no complications or took any medications other than vitamins during my pregnancy.
One daughter was diagnosed as PDD-NOS at age 3. The other is not on the spectrum. They are now 7 years old. Explain that——From my own research I have found that generally with identical twins they are both on the spectrum and with fraternal usually only one is.

kept loosing weight in the six to eight months and had to have a home care nurse 2 to 3 days a week. We had to keep her on iv fluids ,2 bags a day. Tyler was consuming everything Amy digested, plus she had trouble keeping anything down. I finally found she could keep down choc milk if she drank it slow.It was really hard for her to eat or drink. When Tyler was born, He was perfect and mommy was good too. Tyler developed normaly and at 15 months he just quit talking and great grandma spotted this, and said something is not right. She was right. He had mild My daughter-in-law suffered her whole pregnancy with our Tyler(first child). She to moderate autism with the spectrum.

Just one more comment we wondered about was that Amy had worked at a bread store before and during her pregnacy. There is so much talk about mercury and she used those big racks which are full of mercury ? (are they not?)

I hope you can have some input to this curious family’s experience. I also wanted to add my son, daughter-in-law and myself lived together through these trying times. We were all there to help my sweet AMY.

My name is Katie and i have a 21 year old autistic child. He was the best child up until about september when something snapped in him, he has become very agreesive and violent, he is now self-mutalating him self by digging hole on his body. we have been to three different hospitals and no one is willing to take him becuase he is non verbal, we live in michigan but are willing to travel anywhere to get him help. His medications were not changed until the behavior became an issue, nothing has changed in his life. Has anyone ever had this happen to their child? Does anyone have any help for us? we are despriate and in urgent need of help. Please help

I have a 20 year old son with severe autism. He is also violent. He has an absessed tooth which is bothering him. he has an appointment in October to get the tooth pulled out in the hospital. he is on a list if someone cancels. I was wondering if your son is in pain or not feeling good. I live about an hour away from Madison, WI. My e-mail address in wbmcpherson@netzero.net if you want to talk.